In his latest book of the same name, the 56-year-old Marin County (Calif.) author and builder of pioneering online communities such as Electric Minds argues that ubiquitous mobile Internet communications are spurring a new social revolution. The early signs include urban hipsters using the Web to arrange ad-hoc "swarms" of people for fun and political action, as well as Filipino protesters mounting rallies via cell-phone text messages.
True to form, Rheingold ends up with a provocative question: "What can you do when you have a billion people walking around with computing devices connected at high speeds?" He's not sure exactly what tangible business applications might result. But it's a good bet he's onto something big once again.